Bonding of lignocellulosic material, such as wood, is widely used commercially, such as in the manufacture of particle board, laminated wood products, and plywood. In present commercial bonding procedures, an adhesive is employed, which is spread or otherwise applied to the surface of the material, and penetrates the wood structure whereby bonding is effected primarily by the adhesive. Procedures have been proposed to effect such bonding by chemical reaction between reagents and the wood through formation of wood-to-wood chemical bonds, but have not met commercial acceptance.
For example, the patent to Wilson, U.S. Pat. No. 2,639,994, dated May 26, 1953, discloses a method of bonding lignocellulosic material wherein relatively small wood particles, such as wood shavings, are bonded by adding water to increase the normal moisture content, spraying with a dilute solution of an acid, placing the material in a conventional board mold and pressing in a press at an elevated temperature. No teaching is made in this patent that relatively large plywood veneers can be so treated to form plywood nor is the reaction with acid an oxidizing reaction. Glab, U.S. Pat. No. 3,033,695, dated May 3, 1962, discloses a process wherein wood particles may be first digested in an autoclave with acid, such as nitric acid, and then subsequently molded in a press.